In its lawsuit, Top Rank complained it has promoted the featherweight (126-pound maximum) Gamboa for almost three years at a cost of millions of dollars.

The suit says that under Top Rank’s financial commitment and stewardship, Gamboa "is on the verge of stardom" and that it booked him for the April 14 Mandalay Bay fight, to be televised on HBO, against fellow undefeated fighter and former world lightweight champion Brandon "Bam Bam" Rios.

Gamboa later backed out of this deal, Top Rank complained, saying in the lawsuit that if his actions are left unchecked, they "would do untold reputation damage to Top Rank and its relationships with other fighters, promoters and the boxing public."

Top Rank has now lined up another Cuban fighter, World Boxing Association interim lightweight champion Richard Abril, to fight Rios on April 14 at Mandalay Bay.

"I think that the evidence will show that the promotional contract between Gamboa and Top Rank has expired, and that there clearly was never any agreement to fight the Brandon Rios fight," Gary told RingTV.com.

Gary and Gamboa have not yet filed a response to the Top Rank lawsuit, which was filed by attorneys at the law firms Campbell & Williams in Las Vegas and O’Melveny & Myers LLP in Los Angeles.

The Rios/Abril bout -- and other fights that night at Mandalay Bay -- will be produced by Top Rank and distributed live by HBO on a pay-per-view basis in a telecast that also includes Juan Mánuel Márquez fighting in Mexico City against Sergey Fedchenko, Top Rank announced Saturday.

While HBO won't be producing the fight telecast, its agreement to distribute the show was praised by Top Rank.

"Top Rank owes a great deal to its sponsors, Mandalay Bay and HBO for its continued support of our event," Top Rank President Todd duBoef said in Saturday's statement.